Beetles – an overview:

This page provides an overview of beetle pests in vegetable crops. The related tools listed at the end of the page provide detailed information about their identification, damage and management. It is important to be able to identify insect pests such as beetles, and to have unknown species expertly identified so that they can be appropriately managed.
Beetles are the largest and most diverse order of insects, and have mouthparts designed for biting and chewing. They can cause damage to a wide range of vegetable crops across Australia. Beetles come in a large variety of colours and shapes and occur. There are exotic beetle species that present a threat to Australia, including Carrot weevil (Listronotus oregonensis and L. texanus) and Colorado potato beetle (Leptinotarsa decemlineata).

Beetle species, hosts, and damage:

Beetle species

Description

Host vegetable crops

Primary damage
Weevils – Vegetable weevil (Listroderes difficilis); Fuller’s rose weevil (Asynonychus cervinus); White-fringed weevil (Graphognathus leucoloma) Weevils are box-shaped beetles with a distinctive ‘snout’. Adults are grey-brown in colour. Leafy vegetables; Brassica vegetables; cucurbit vegetables; carrots; beetroot; parsnips; parsley; beans; eggplant; tomatoes. Adults can chew leaves and larvae feed on leaves and growing tips or roots and underground stems, depending on the species. Plants become stunted and may die.
Wireworm (Family Elateridae – Arachnodima spp., Agrypnus spp.) and False wireworm (Family Tenebrionidae) Wireworm adults are commonly known as ‘click beetles’ and have brown or black torpedo-shaped bodies. False wireworm adults are a dull grey, brown or black, and either oval or slender in shape. Brassica vegetables; cucurbit vegetables; leafy vegetables. Most damage occurs below the soil surface. Larvae chew and bore into stems and plants may wilt and die.
African black beetle (Heteronychus arator) Adults are shiny and black. Potato; cucurbit vegetables Adults chew stems just below ground level and older larvae feed on roots. Plants may wilt and fall over.
28-spotted ladybird beetle – Cucurbit or Leaf eating ladybird (Henosepilachna vigintioctopunctata) Adults are relatively larger than other ladybird species. Orange in colour with 28 black spots on their back. Cucurbit vegetables; Leafy vegetables. Unlike other ladybird beetles, the adults and larvae feed mainly on leaves. This results in ‘windowing’ damage to leaves. Larvae may also injure the rind of fruit.
Pumpkin beetles – Banded (Aulacophora hilaris); Plain (Aulacophora abdominalis) The plain pumpkin beetle adult is uniformly orange. The banded pumpkin beetle is orange, with four distinct large black spots. Cucurbit vegetables. Adults feed on leaves, flowers and small fruit. Can defoliate and kill seedlings and small plants.
Flea beetles – Brown (Chaetocnema spp.); Striped (Phyllotreta undulata); Black (Psylliodes spp.) Flea beetles are 1-3 mm long with enlarged hind legs enabling them to leap from leaf surfaces when disturbed. Asian leafy brassicas; beans. Beetles chew small holes in leaves.

Management:

Some beetles are only a minor and occasional problem. As for other pests it is important to control weeds, cleanup residues soon after harvest and use suitable crop rotations to minimise pest numbers. Cultivation or a long weed-free fallow before planting may help decrease pest pressure. Always maintain seedling health.

Insecticides may be used if pest numbers become high and in some instances, spot-spraying may be sufficient or cost-effective. Check the APVMA website for registered chemical options.

Source of information and related tools: